Eagler's Nest
Engines => 2 Cylinder => 1/2 vw => Topic started by: grdev on April 12, 2015, 04:50:07 PM
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How much thrust does the 1/2 VW produce? Im told my 1/3 Corvair with redrive will produce 250
pounds. How will that work on my XL, any thoughts? Engine is running, should have Vids next week to show.
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Gil, I don't know what a 1/3 Corvair will produce in thrust.
We made static thrust measurements for our LEU with a couple different props. This was a 1/2 VW producing 29 hp (as measured by the wood bar dyno method);
unknown 54x20, 3120 rpm, 101 lbs
Hegy 54x22, 3090 rpm, 93 lbs. Note, we never flew the 54x20 because it was too sluggish on take-off roll. We found the 54x22 to be much more peppy on ground roll. (was it due to pitch difference, or different mfg, or both?)
I was taking notes as others reported their prop info. Here is what the notes say:
45 hp Casler, Tenn 58x24, 2800 rpm, 170 lbs (unloads during climb, rpm goes to 2950)
45 hp Casler, unknown 58x22, 3050 rpm, 180 lbs
78x92 stroke/bore, Tenn 54x24, 3400 rpm, 195 lbs
78x92, unknown 54x24, 3000 rpm, ? lbs
86x94 Casler, Tenn 58x24, ? rpm, ? lbs (great climb reported)
Keep in mind that static thrust is not a full indicator of performance in flight. A prop could be partially stalled during full throttle static test, producing a lower lbs pull, but as soon as the airplane gets forward speed, it will unstall and start working hard. A prop that is working its hardest at no forward speed may give out as it gets airspeed. I think these airplanes need a prop to be working the best at climb speeds.
Your 1/3 Corvair will have some stroke/bore, maybe close to some of the above, theoretically similar power with similar prop performance.
I know this does not answer your question, but hopefully some help.
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Gil, if your engine is producing similar power as the larger 1/2 VWs, your redrive version will fly an XL very nicely. The redrive allows a larger diameter prop and I suspect 250 lbs is a possibility.
The direct drive is what limits our VWs to less thrust than a geared engine.
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Gil, totally missed the word "redrive"! I believe Sam is right. Be sure to do all the testing and let us know.
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Gil, if your engine is producing similar power as the larger 1/2 VWs, your redrive version will fly an XL very nicely. The redrive allows a larger diameter prop and I suspect 250 lbs is a possibility.
The direct drive is what limits our VWs to less thrust than a geared engine.
The trade-off I forgot to mention is the large diameter prop, while yielding great climb performance, may limit top speed. It will be a matter of finding the best compromise between the two.
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Thanks for replies. I would much rather have the short field advantages rather than speed. I'm looking forward to the Low & Slow aspect. Ultra Vair has build a 58 x 26 prop for the engine and claims it will produce 250 pounds thrust. I plugged those numbers in a thrust calculator and that would require around 45 HP. Hope my XL isn't going to be a fat XL, guess I will find out soon. I'll post more when I have the engine running and on the airframe.